This invention relates to computerized controls for printing machines, and more particularly to a presetting apparatus for register and color zone adjustment.
At the present time, the major printing machine manufacturers sell computerized printing machine control systems for remote control of ink-dosing elements arranged across the width of the printing machine for applying ink to printing plates, and for remote control of circumferential, axial, and in some cases diagonal or skew register of the printing plates. The adjustments, for example, are entered by an operator at a remote control terminal. Such a system may be provided with a densitometer table for scanning color control strips printed on a test sheet for automatic control of ink density, as is described in Schramm et al. U.S. Pat. No. 4,200,932 issued Apr. 29, 1980 and for which a reexamination certificate issued Apr. 26, 1983.
Computerized press controls have been used for real time and continuous register adjustment for web-fed rotary printing machines. See, for example, Stratton et al. U.S. Pat. No. 4,318,176 issued Mar. 2, 1982. Typically, web registration control systems have optical sensors focused upon axial and skew register marks printed on the web, and may also have an optical sensor detecting an axial or skew reference mark engraved on the plate cylinder. See, for example, Resh U.S. Pat. No. 4,135,664 issued Jan. 23, 1979, and Crum U.S. Pat. No. 3,701,464 issued Oct. 31, 1972.
It is known to scan a printing plate or original print at a location remote from the printing press to estimate the necessary amount of ink for printing or to predetermine appropriate settings for ink dosing keys. Sugawara et al. U.S. Pat. No. 4,233,663 issued Nov. 11, 1980 discloses a system wherein an original print is mounted on a drum and is scanned by an optical sensor. The signal from the optical sensor is processed digitally and the digital signals are classified into 256 levels so that the accumulated value for each level may be adjusted by an individual correction factor representing the amount of ink required to print a picture dot at the corresponding optical density level, before integrating to determine the total amount of ink required to print all the picture dots on the original print. A slightly different system is disclosed in Murray et al. U.S. Pat. No. 3,958,509 issued May 25, 1976 wherein a flat lithographic plate is scanned by a television camera and after normalization, the signal is accumulated or integrated over the inking zones on the printing plate to determine appropriate settings for the ink keys.
The assignee of the present invention has endeavored to develop automatic register control systems for sheet-fed rotary printing machines. Greiner U.S. Pat. No. 4,437,403 issued Mar. 20, 1984 discloses an automatic control method and apparatus for adjusting the register of printing plates in a multi-color printing press before test sheets or proofs are printed. Photoelectric scanners sense right-angle register marks engraved on the printing plates and determine the relative positions of the printing plates without the use of paper. Greiner U.S. Pat. No. 4,428,287 issued Jan. 31, 1984 discloses an apparatus and method for checking and automatically correcting register adjustment of a sheet-fed printing press at the same time as remote densitometeric measurement of an ink density check strip printed on a test sheet for ink fountain key adjustment. Alignment marks printed on the test sheet parallel to the ink density check strip are sensed by a second optical sensor mounted alongside the densitometer which reads the ink density check strip.
The references cited above are only a few of the diverse systems and methods that have been devised for presetting ink dosing and plate register. In general, these methods require measured values to be fed to intermediate memories, and another operation or remote control system is required to transmit adjustments to the ink dosing devices and register adjustment mechanisms. But these various methods are complex and suffer reliability problems due to the number of individual components which may fail. Also, the resulting accuracy of the pre-setting operation is not very high. It is fair to say, however, that remote control systems have evolved to such an extent that the mechanical parts of the printing press subject to adjustment can be automatically adjusted in response to the input of desired values. German Pat. No. 2,922,964, for example, discloses a system for preparing and controlling printing presses including the pre-setting and further adjustment of the inking unit, ink guide, and dampening and folding units.